Currently, the charge coupled device (CCD) is commonly used as an image detector and is widely applied in a scanner for scanning the plane pattern, a digital camera for recording the transient action, a video camera for recording sequential images, and a night vision equipment.
Because the charge packet stored in each storage cell (usually in a linear arrangement) of the CCD will be generated in response to the radiation of light and the magnitude of charge is directly proportional to the intensity of light, the readout signal in each storage cell must be processed by the successive steps to further obtain the information of the image. Moreover, the signal representative of the light intensity in each storage cell of the CCD must be outputted in a sequential manner, thereby reducing the signal-reading speed and decreasing the image recording rate. In addition, it also increases the complexity of rear circuits.
Thus, it is tried by the applicant to improve the above-described drawbacks of the CCD and to develop a preferred photodetector.